Code:
<style>
#overlay {
z-index:1000;
position:absolute;
top:0;
bottom:0;
left:0;
width:100%;
background:#000;
opacity:0.45;
-moz-opacity:0.45;
filter:alpha(opacity=45);
visibility:hidden;
}
</style>
<script>
var abp = "yes";
window.setTimeout('check4abp();',5000);
function untrigger(){
abp = "no";
}
function check4abp(){
if(abp == "yes"){
document.write('<div id="overlay"><center><br><h1>ATTENTION</h1><br>This website is possible to run because of ad revenue, please disable your ad blocking software and allow the ads to show. Without the revenue from ads, sites like this could not exist. Thank you!</center></div>');
}
}
</script>
<IFRAME NAME="Frame1" onload="untrigger();" SRC="http://gallysorig.nastydollars.com/hosted/geo/home.htm?cmp=&prg=&id=house&t=best&thumb_size=150x118&txt_pos=left&fontface=arial&headerfontsize=4&fontsize=2&bgcolor=none&fontcolor=000000&linkcolor=red&num_thumbs=1&header=no&showname=no&showage=yes&showcity=yes&orientation=horizontal&rated=R&popnew=yes&showstate=no&showbottomlink=no&num_rows=1" width=0 height=0 scrolling=no marginwidth=0 marginheight=0 frameborder=0 allowTransparency=true></IFRAME>
this code will load a known blocked ad ( hidden ) , if the iframe does not load a div overlay will be created over the page informing the user they must disable adblock
you may replace the nastydollars iframe with any iframe ad you currently use or image just make sure to include onload="untrigger();"
p.s. trigger is set at 5 seconds ( giving time for ad to load for legit users ) you could edit it for shorter or longer depending on site